Syringes typically include a plunger which is a rigid stem used to move a slidable piston axially through a solution-filled barrel to push solution through a nozzle at the end of the barrel.
In order to ensure that all the solution in the barrel is administered through the syringe nozzle, the plunger stem must be at least as long as the syringe barrel. For small volume syringes, 5 cc and 10 cc syringes, for example, the syringe barrel may be approximately three to four inches (3-4") long. Thus, the small volume syringe plunger stem is often in the range of approximately three to four inches long. Usually a user, even with small hands, can grasp the syringe barrel at the flange tabs between two fingers and extend the thumb to the distal end of the extending plunger stem. Then, when the user applies force on the plunger pushing surface, the piston moves through the barrel and solution is administered through the end nozzle.
However, for larger syringes, for example, 50 cc or 60 cc syringes, the barrel is typically longer than four inches (4") and often longer than five inches (5"). Consequently the plunger is also longer than approximately four inches. A user with small hands will have great difficulty in using these large syringes with only one hand. For example, a person with small hands will have great difficulty in positioning the wide diameter syringe barrel between two fingers and firmly hold the barrel while extending the thumb rearward four inches or more to the plunger pushing surface. Even if the user accomplishes this stretch of the hand, the small handed user may have difficulty generating enough axial force to push the plunger into the barrel to begin administration of the solution.
Often a small handed riser using a large volume syringe must resort to two handed operation of the syringe. In many situations, two handed use limits the user's ability to perform other tasks. These other tasks include opening or closing flow control devices, or other manipulation that are normally most efficiently performed concurrent with the fluid administration. Thus, it is a disadvantage to have a large volume syringe that cannot be used by all users in the same one-handed manner that is used for small volume syringes.
It is therefore desirable to provide a syringe plunger for large volume syringes that would accommodate one-handed administration by small handed people. Such a syringe plunger would enable a small handed person to perform the procedures in an expected manner.
The present invention provides a syringe plunger with an intermediate pushing surface positioned on the stem between the proximal end of the stem and the distal pushing surface of the stem that will accommodate one-handed administration of most syringes by small handed persons.